Wirraway rivet counting...

[Derek_B]

I'm (slowly) working on several Wirraway builds at the moment, and thought I might share a few details of Wirraways here for your interest and edification! 

 

The first item of interest is the correct radio aerial detail for the Special Hobby kit depicting A20-444 "NV-J". I've corrected the box-art to show how the aerial should be configured (the two wires out to the wing-tips are missing from the box art) as well as to show the correct cowling configuration for this aircraft (no air intake on the upper front edge of the cowling).

 

 

Hope you find this of interest. 

 

The first of my builds is here:

 

Edited August 28, 2021 by Derek_B
extra info

[dragonlanceHR]

Yes! Thank you. As the RedRoo correction set is unavailable in the upper hemisphere, a good how-to walkthrough for corrections is most welcome.

Cheers,

Vedran

[Graham Boak]

I'll be interested in these too.  My impression is that the MPM/SH Wirraways are too fat, so just what you (Derek) think could influence me a lot.

[donaldAnderson]

Thank you!  Just noticed the wavy upper/lower camouflage demarcation line. Is this correct, too, for the period?

[Julien]

2 hours ago, Derek_B said:

I'm (slowly) working on several Wirraway builds at the moment, and thought I might share a few details of Wirraways here for your interest and edification! 

 

The first item of interest is the correct radio aerial detail for the Special Hobby kit depicting A20-444 "NV-J". I've corrected the box-art to show how the aerial should be configured (the two wires out to the wing-tips are missing from the box art) as well as to show the correct cowling configuration for this aircraft (no air intake on the upper front edge of the cowling).

 

 

 

Hope you find this of interest. 

 

More details on my builds coming soon...

Looking forward to your builds, remember to put them in the WIP or ready for inspection threads applicable.

 

 

1 hour ago, dragonlanceHR said:

Yes! Thank you. As the RedRoo correction set is unavailable in the upper hemisphere, a good how-to walkthrough for corrections is most welcome.

Cheers,

Vedran

I have had no issues ordering from Red Roo here in the UK, pretty good service all in.

[dragonlanceHR]

22 minutes ago, Julien said:

I have had no issues ordering from Red Roo here in the UK, pretty good service all in.

Julien, the set is OOS sice forever and hasn't been restocked, to my knowledge.

[Derek_B]

2 hours ago, donaldAnderson said:

Thank you!  Just noticed the wavy upper/lower camouflage demarcation line. Is this correct, too, for the period?

Donald, yes the wavy demarcation line is correct for this particular 23 Squadron aircraft. Many 23 Squadron aircraft were delivered with Aluminium undersides out of the CAC factory, and when the orders came through to repaint the under-surfaces with Sky Blue (Air Board memo SAS 9984 “Camouflage of second line aircraft” of 29 December 1941), I'm assuming the squadron's painters adopted some artistic licence! Also the paint under the engine cowling was not strictly "regulation" either. Also the fuselage roundel is much further forward than the "regulation" position.

[Derek_B]

14 hours ago, Graham Boak said:

I'll be interested in these too.  My impression is that the MPM/SH Wirraways are too fat, so just what you (Derek) think could influence me a lot.

 

Graham, yes they do bulge where they should not (both the 1/72 and 1/48 versions)... stay tuned and I'll explain what I see as the issues...

[Ed Russell]

18 hours ago, dragonlanceHR said:

the set is OOS sice forever and hasn't been restocked, to my knowledge

It has been reissued twice and we will do a fourth run soon. Make sure you are on our mail list to see the announcement. They usually sell out fairly quickly.

[dragonlanceHR]

3 minutes ago, Ed Russell said:

It has been reissued twice and we will do a fourth run soon. Make sure you are on our mail list to see the announcement. They usually sell out fairly quickly.

Thanks, will do!

[Derek_B]

@Graham Boak in reference to the chubbiness of the MPM/SH kits, for reference, here is a link to my detailed 3-view drawings of the CA-1 Wirraway:

 

https://dbdesignbureau.net/2021/08/25/cac-wirraway-mk-i-ca-1/

 

Then, here is a discussion about all the other 3-view drawings which I found, and the problems they pose (which is why I created my own drawings!):

 

https://dbdesignbureau.net/2021/08/25/the-cac-wirraway-scale-drawings-saga/

 

I don't have any insider knowledge, but from the looks of the moldings the 1/48 SH kits were based on the Caruana drawings from Scale Aviation Modeller International, November 2003.

 

First, let's look at some kit moldings and compare them to accurate dimensions. The photo below shows three different 1/72 scale fuselage moldings. The MPM and High Plains fuselages are just taped together, the Special Hobby fuselage is already glued. The incorrect bulge of the fabric side-panels on the MPM and SH kits is immediately obvious. So too is the incorrect fuselage/wing fillet.

 

 

The widest part of the fuselage on a full-size Wirraway is 46" wide, which translates to 16.2mm at 1/72 scale. The model widths are as follows:

MPM                            18.5mm  (114.0% of scale value)

Ventura / High Plains / Jays   16.4mm  (101.1% of scale value)

Special Hobby                  18.4mm  (113.4% of scale value)

 

So you can see that the MPM and SH models are much fatter than they should be. The extra fuselage width also translates to a wider cockpit opening and wider canopy, which is not to scale. For reference, the canopy on the Wirraway is the same width as the canopy on a T-6 Texan or a Harvard III (but the framing is different).

 

By the way, I filed a small extension to the "ledge" along the canopy rails onto the MPM and SH fuselages shown above (highlighted by the green arrow) - these are not on the original moldings. Also, I've filed the over-sized wing/fuselage fillets off the MPM fuselage shown above, straight out of the box they are the same as the SH fillets.

 

If we look at the fuselage profile for the MPM kit, we see the aft fuselage becomes too thin at the rear and the cockpit canopy is slightly too far aft. The rear fuselage "droops" a little (see more on this further below).

 

 

Here is the Ventura / High Plains Models / Jay's Models fuselage aligned over the accurate drawing. This is clearly the best scale representation of the three different 1/72 kits. However it's not perfect, as the aft fuselage is slightly too long. But that is relatively easy to correct.

 

 

Next up will be a comparison of the Caruana scale drawings to accurate drawings...

 

Edited September 4, 2021 by Derek_B
extra info

[Derek_B]

Since the Special Hobby kits are based on the Caruana 2003 drawings (which appear to be based on the Pawlowicz 1973 drawing which was published in Aeromodeller magazine January 1973), I thought it would be useful to compare these drawings against accurate drawings based on factory drawings and aircraft measurements. 

Below is the fuselage profile view showing my drawing (red) overlaid on the Caruana drawing (black). I have aligned the thrust line of both drawings, and the firewall. The actual aircraft fuselage is considerably deeper than the Caruana drawing, and the aft end of the aircraft sits higher. The canopy is also taller than the Caruana/Pawlowicz drawing.

 

 

And below is the fuselage plan view, showing the extra width and curvature in the Caruana/Pawlowicz drawings when compared to an accurate outline.

 

 

Next I'll get some photos of the SH 1/48 fuselage compared with drawings. Sadly it shows the same errors as the drawings above.

 

Edited April 25, 2023 by Derek_B

[Derek_B]

Here are two photos showing the SH 1/48 fuselage compared with scale drawings. 

 

First, the comparison to the Caruana/Pawlowicz drawing, which is not accurate, but which the SH molding matches almost perfectly...

 

 

And next, the comparison to my drawing, which IS accurate, and shows how the SH molding has the canopy rails too low and the aft end of the fuselage sagging and too short...

 

 

(Note that I aligned the molding to the firewall on the drawing (marked by red arrows) but even though I positioned the camera a good distance from the part, and zoomed in with a 10x optical zoom, parallax has introduced a mis-alignment between the firewall of the part and the drawing).

 

I also compared the width of the kit against the correct scale values. At 1/48 scale, the fuselage should be 24.3 mm wide. The kit measures 26.1 mm wide (107.2% of the scale width).

 

So the bad news is that this kit doesn't really form the basis of a good 1/48 scale model of the Wirraway. I don't think that's news to many here. For my 1/48 build, I'm toying with using the SH Wirraway wings mated to a Monogram T-6 fuselage (shortened slightly at the tail end). I also have a vac-form Sierra kit in my stash which could also go with a set of SH wings... but I've never attempted a vac-form kit in all my days... this will require some more thinking...

Edited September 2, 2021 by Derek_B

[gingerbob]

Funny you should mention that- would you be able to show the Monogram fuselage against your drawing?

[Derek_B]

@gingerbob here you go, see below. The width of the Monogram T-6 fuselage is 23.5 mm, just a shade under the desired width of 24.3 mm. Of course the tail-end is slightly longer but that is to be expected (since later aircraft in the NA-16 family had 4" added aft of their tail-wheel to help with spin recovery) and easily fixed. I marked the Wirraway rudder separation line with dark blue arrows...

 

 

I'm encouraged by the look of this... the wing/fuselage fillet is correct, the aft fuselage is deeper and doesn't droop, the cockpit rails are right on, plus the fuselage is the correct width. With all the surface detail raised, it will be relatively simple to sand it off and scribe/sculpt the new surface detail... am I dreaming?

 

Edited September 2, 2021 by Derek_B

[alt-92]

At a guess, I'd say sculpting the stringers and fabric with Surfacer 500 or something similar may put it to the desired width. 
Interesting use of the Monogram T-6  

[dogsbody]

From member @Geoffrey Sinclair:

 

From archives file MP1472/1 4.

 

 

 

 

 

 

Chris

[Derek_B]

Interesting to see that Special Hobby have re-boxed their CA-9 Wirraway with two new decal choices.

 

They have carried over several mistakes in the kit and instructions. Some quick corrections if you plan on building one:
a) Parts B14 should be deleted (on the real aircraft, the retract cylinders are inside the wing).
b) All references to paint colour "C364 Aircraft Gray Green" should be changed to "H8/C8 Silver", as Wirraways did not have interior green paint anywhere in the cockpit, it was entirely silver.

c) For A20-617 the roll-over truss behind the pilot (and only the roll-over truss) should be painted Foliage Green for this aircraft, not silver as shown in the otherwise excellent box-art.

d) For A20-617 the propellor hub should be black, same as the propellor blades (another minor error on the box-art).
Also, note that A20-637 was a CA-16 Wirraway, not a CA-9 as described in the colouring notes.

 

 

 

Here are two photos of A20-617 from the box-art, with 86 Squadron at Bohle River airstrip, Queensland (very close to Townsville), with Mount Stuart in the background (note the black propellor hub):

 

 

And here's an image of Bohle River from the air, from the Australian War Memorial (see the box-art):

Edited March 11 by Derek_B

[Graham Boak]

I presume that the plastic is the same in this release as before.

 

A couple of points that I think need clarifying, if you would, please.

In what ways do the cockpit framing differ from that of the Harvard - windscreen excepted.

In your planview of the plans comparison, the canopies appear to be the same size but you say (and I believe) that the SH canopies are wider.  MPM is just the over-company for Special Hobby.)

 

Adding one point, the starboard side intake on the new box art is new to me - at least I don't recall noticing it before.  (Must check Wirraway references.)  Is it on the new release parts?

 

I've considered chopping the SH kits apart or remove the bulge, but it all seems like a lot of work that might not come out terribly well and runs the risk of ending up with too short a span.  I wonder if it might be better to use an Airfix (or indeed other) T-6  for the centre fuselage and use thin microstrip pieces for the fabric's longerons.  (Which would help reduce the stash size...)  An NA-57 as a base is probably unobtainable nowadays, and it might be worth checking its fuselage width too!

 

[tempestfan]

On 9/1/2021 at 2:24 PM, Derek_B said:

Since the Special Hobby kits are based on the Caruana 2003 drawings (which appear to be based on the Pawlowicz 1973 drawing),

 

 

I think I'll better say nothing 😇

On 9/2/2021 at 1:56 PM, Derek_B said:

 

I'm encouraged by the look of this... the wing/fuselage fillet is correct, the aft fuselage is deeper and doesn't droop, the cockpit rails are right on, plus the fuselage is the correct width. With all the surface detail raised, it will be relatively simple to sand it off and scribe/sculpt the new surface detail... am I dreaming?

 

An alternative to the strip method Graham suggested could be the use of thin plasticard, scored from the inside with a ballpen to simulate the stringers, as some kind of top "planking", which could give an effect of flat facets, at least on the centre fuselage which appears to have little taper if any. This could help to avoid a "Starving cow syndrome".

 

BTW, many thanks for generously providing those links - I have downloaded your drawings (even though I do not know if I will ever buy build another kit, let alone a Wirraway) and bookmarked your site. BTW, didn't Kookaburra have one of their little softbacks on the Wirraway, or did they only cover the Boomerang? But anyway, if they did (or had done), they would most likely have used a company publicity 3-view as a basis like that CAC employee probably did.

[Shorty84]

On 9/2/2021 at 12:15 PM, Derek_B said:

Here are two photos showing the SH 1/48 fuselage compared with scale drawings. 

Many thanks for this comparison. Unforunately I saw this after purchasing the kit (although I noticed on a build I saw online that there is something wrong with the clear parts. That will teach me).

My original plan was to use some parts of the Italeri (ex-Occidental) Harvard kit (like the clear parts and engine) in order to get a Harvard Mk.I. The plan still stays but I think basing it mostly on the Italeri parts results in a more accurate model than the other way around. Now I just need to find a way to represent the fabric covered parts convincingly...

 

Cheers

Markus

[Graham Boak]

Just to clear up one point I raised earlier: the AZ NA-57 kit does not have a fat fuselage.  I also found that I have a spare NA.57 so this sorts out the centre and aft fuselages.  There's still the section between the engine and the central fuselage but it may be possible to file this to a thinner section.  If not I've a spare Airfix fuselage part.  (I have a spare one because it was gong to be a Yale, but RS brought out one.)

 

Does anyone know if the canopies on the new SH Harvard are available as spares?  

.  

[Derek_B]

17 hours ago, Graham Boak said:

I presume that the plastic is the same in this release as before.

 

Yes, no change, same plastic and resin parts.

 

17 hours ago, Graham Boak said:

 

In what ways do the cockpit framing differ from that of the Harvard - windscreen excepted.

 

In your planview of the plans comparison, the canopies appear to be the same size but you say (and I believe) that the SH canopies are wider.  MPM is just the over-company for Special Hobby.)

 

Wirraway cockpit glazing is slightly lower than that of a Harvard (by about 1", so it hardly shows up at 1/72 scale). Although the glazing is overall shorter, the flat side panels are about 3/4" taller. Wirraway frames don't have any fillets in the corners and they don't have broader sections where the emergency release handles are mounted inside the central frame of the two sliding canopy sections. I'll try to add some photos when I get a chance.

 

The 1/72 SH canopy is 12.9mm wide at the base of the pilot's sliding canopy. The correct scale value should be 11.4mm.

The 1/72 MPM canopy is 12.7mm wide, a little tricky to measure as it is vacuum-formed.

 

17 hours ago, Graham Boak said:

Adding one point, the starboard side intake on the new box art is new to me - at least I don't recall noticing it before.  (Must check Wirraway references.)  Is it on the new release parts?

 

 

The starboard side intake on the engine cowl on the latest box-art is correct. The new-release contains the same moldings as the previous release, but the resin cowl incorporates the starboard side intake on the engine cowl. The injection-molded cowl does not incorporate the starboard-side intake, which is correct for Mk.I and Mk.II Wirraways before they all had their engine cowls replaced following the issue of Wirraway Order No. 108 on 26 March 1943. See my drawings here: https://dbdesignbureau.net/2021/08/25/cac-wirraway-mk-i-ca-1/ (plates 4a and 4d explain the different cowlings fitted to Mk.I Wirraways later in their service life.

[Derek_B]

8 hours ago, Graham Boak said:

Just to clear up one point I raised earlier: the AZ NA-57 kit does not have a fat fuselage. 

 

That's right Graham, so yes, you could use sections of the Azur NA-57 kit to replace the "fat" parts of the Special Hobby kit. 

Or you could combine fuselage parts from a Jay's Models Wirraway kit (the old High Plains / Ventura kit re-boxed) with Special Hobby wings...

[Derek_B]

13 hours ago, tempestfan said:

An alternative to the strip method Graham suggested could be the use of thin plasticard, scored from the inside with a ballpen to simulate the stringers, as some kind of top "planking", which could give an effect of flat facets, at least on the centre fuselage which appears to have little taper if any. This could help to avoid a "Starving cow syndrome".

 

Yes, I've toyed with this idea. A friend of mine did a quite nice Wirraway in 1/48 many years ago, using this method to replace the side panels of a Monogram/Revell Texan.